Journal Article

Contributions of stratospheric thermal anomalies to the intensification of intense summer Arctic cyclones

Tao, Wei, Lu, Chuhan, Kong, Yang

2024

Overview

Arctic cyclones, as significant weather systems at high latitudes, are often accompanied by strong winds or heavy precipitation, leading to prolonged and more destructive disasters. In this study, we identified summer (JJAS) Arctic cyclones in the ERA5 reanalysis dataset from 1979 to 2022 using a machine-learning cyclone identification and tracking algorithm. We selected 40 sets of the strongest cyclones on the northern edge of Eurasia (NEE), one of the most identifiable Arctic Frontal Zones, over the past 44 years to assess the role of tropopause polar vortices (TPVs) in intense summer cyclones by using the Weather Research and Forecasting model (WRF). Our sensitivity experiments show that removing the horizontal temperature gradient of the lower stratosphere significantly reduces cyclone intensity, particularly for TPVs-matched cyclones, increasing by 7.4 hPa at their maximum intensity moment (2.8 hPa for TPVs-unmatched cyclones). TPVs-matched cyclones typically exhibit a lower tropopause and an “upper warm-lower cold” thermodynamic structure. High potential vorticity (PV) induced by the downward intrusion of TPVs due to the thermal structure closely links with the intensified development of these cyclones, leading to prolonged lifetimes. On the other hand, TPVs-unmatched cyclones display a distinct frontal structure in the lower troposphere but are not sensitive to changes in the upper-level horizontal temperature gradient. This may help to highlight the role of TPVs downward intrusion on TPVs-matched intense cyclones on NEE.

• Publisher: Springer Berlin Heidelberg,Springer,Springer Nature B.V
• Subject: Algorithms / Arctic cyclones / Arctic fronts / Arctic region / Arctic zone / artificial intelligence / Atmospheric temperature / Causes of / Climate models / Climatology / cold / Comparative analysis / Cyclones / data collection / Disasters / Earth and Environmental Science / Earth Sciences / Environmental aspects / Eurasia / Forecasting models / Frontal structure / Frontal zones / Geophysics/Geodesy / Heavy precipitation / Identification and classification / Intrusion / Low pressure systems (Meteorology) / Lower stratosphere / Lower troposphere / Machine learning / Oceanography / Original Article / Polar vortex / Potential vorticity / Stratosphere / Strong winds / Summer / temperature / Temperature gradients / Thermal structure / Tropopause / Troposphere / Vorticity / Weather / Weather forecasting / Winds